Category Archives: Astronomy

Like millions of other people, Wanda Diaz Merced plans to observe the August 21 total solar eclipse, when the moons shadow will sweep across the sun and, for a few brief moments, coat parts of the United States in darkness. But she wont see it. Shell hear it.

Diaz Merced, an astrophysicist, is blind, with just 3 percent of peripheral vision in her right eye, and none in her left. She has been working with a team at Harvard University to develop a program that will convert sunlight into sound, allowing her to hear the solar eclipse. The sound will be generated in real time, changing as the dark silhouette of the moon appears over the face of the bright sun, blocking its light. Diaz Merced will listen in real time, toowith her students at the Athlone School for the Blind in Cape Town, South Africa, where she teaches astronomy.

Its an experience of a lifetime, and they deserve the opportunity, Diaz Merced said.

To capture the auditory version of this astronomical event, the team turned to a piece of technology measuring only a couple inches long: the Arduino, a cheap microcomputer popular with tech-savvy, DIY hobbyists. With a few attachments, Arduinos can be used to create all kinds of electronic devices that interact with the physical world, from the useful, like finger scanners that unlock garage doors, to the silly, like motion-detecting squirt guns. Diaz Merceds collaborators equipped an Arduino with a light-detecting sensor and speaker, and programmed it to convert light into a clicking noise. The pace of the clicks varies with the intensity of the sunlight hitting the sensor, speeding up as it strengthens and slowing down as it dims. In the moments of totality, when the suns outer atmosphere appears as a thin ring around the shadow of the moon, the clicks will be a second or more apart.

Allyson Bieryla, an astronomy lab and telescope manager at Harvard, will operate the Arduino from Jackson Hole, Wyoming, inside the path of totality. She will stream the audio on a website online, which Diaz Merced will open on her computer in Cape Town.

So far, Bieryla says, the real challenge has been trying to find a light sensor thats sensitive enough to get the variation in the eclipse. In totality, the sun will appear about as bright as a full moon at midnight. The team has tested the Arduino at night, under the moonlight, to make sure it can pick up the faint luminosity.

Diaz Merced, a postdoctoral fellow at the Office of Astronomy for Development in South Africa, was diagnosed with diabetes as a child. In her early 20s, when she was studying physics at the University of Puerto Rico, she was diagnosed with diabetic retinopathy, a complication of the disease that destroys blood vessels in the retina. Her vision began to deteriorate, and a failed laser surgery damaged her retinas further, she said. By her late 20s, she was almost completely blind. She recalls watching a partial solar eclipse in 1998 in Puerto Rico, when she still had some sight.

I was able to experience the wonderfulnessof the sun being dark, of having a black ball in the sky, she said. That is why it is important to use the sound in order to bring an experience that will bring that same feeling to people who do not see or are not visually oriented.

While Diaz Merced experiences the eclipse from a classroom in Cape Town, Tim Doucette will observe the event at a campground in Nebraska, smack-dab in the path of totality. Doucette is a computer programmer by day and an amateur astronomer by night. He runs a small observatory, Deep Sky, near his home in Nova Scotia in a sparsely populated area known for low light pollution and star-studded night skies.

Doucette is legally blind, and has about 10 percent of his eyesight. He had cataracts as a baby, a condition that clouds the lenses of the eye. To treat the disease, doctors surgically removed the lenses, leaving Doucette without the capacity to filter out certain wavelengths. His eyes are sensitive to ultraviolet and infrared light, and he wears sunglasses during the day to protect his retinas. Without shades, Doucette said he cant keep his eye open in the brightness of day. But at night, his sensitivity becomes an advantage. With the help of a telescope, Doucette can see the near-infrared light coming from stars and other objects in the sky better than most people.

My whole life, Ive always been asking people for help, saying, hey, what do you see? Doucette said. When I stargaze with people, the tables are reversed.

Doucette sees best at night, safe from the glare of the sun. He uses starlight to guide him during the short walk from his observatory to his home. When Im walking down the road, especially during the summer months, the Milky Way is just this incredible painting going from north to south, he said. Its millions and millions of points of light. Its like a tapestry of diamonds against a velvety background.

Doucette, armed with his camera equipment, will observe the eclipse with dozens of members of the Royal Astronomical Society of Canadas Halifax Center, an association of amateur and professional astronomers. He has only witnessed partial solar eclipses in the past. It should be quite interesting to see what the effect is because of my sensitivity, he said. During totality, when day becomes night, some objects in the sky may become visible, thanks to his sensitivity to their light.

Doucette will wear eclipse sunglasses over his regular pair. Eclipse glasses protect the eyes from sunlight so viewers can look directly at it without hurting their eyes, and they can be bought online for a few dollars. Doucette urged eclipse viewers to use them, citing stories hed heard of people looking at the sun during an eclipse and waking up blind the next morning, their retinas burned. The shades are necessary before and after totality, when the sun is only partially eclipsed and a thin crescent shines with typical intensity.

Once the eclipse is in totality for about two and a half minutes, Im told that its safe to take the glasses off, but Im not willing to risk it, Doucette said. Ill still keep my sunglasses on either way.

Local astronomy professors say Spartanburg County residents should at least try to get to the southern part of the county on Aug. 21 to experience the full solar eclipse.

The eclipse path runs through Spartanburg County, but only the southern and southwestern portions of the county will see 100 percent totality that Monday afternoon. Events are scheduled across the Upstate, and state public safety officials are preparing for increased traffic on state roads.

Astronomy professors Andy Leonardi of the University of South Carolina Upstate and Bill Yarborough of Converse College said the eclipse will be a once-in-a-lifetime sight.

What else will be visible in the sky during the eclipse?

Leonardi:Not so much when youre looking up at the sun and the moon itself. The wispy corona that will appear during the eclipse will be pronounced. The little extra bit of light will make the sky look a little different.

Yarborough:What you can see is whats called the suns corona. Surrounding the sun is a very tenuous region thats far, far hotter than the surface. It doesnt emit enough light for us to normally see it. Its like a huge, bright halo. When the moon completely blocks the disk of the sun we normally see, the corona will light up the sky. Its an absolutely incredible view.As far as planets or things of that sort, it wont quite be like a dark night. Itll be like dusk or sunset. Not quite dark enough to see a lot of planets and things like that.

What does it mean that Spartanburg isn’t in the path of totality?

Yarborough:What that means for Spartanburg is, the sun will never be completely blocked. A little edge of sun will still be visible from behind the moon. Its still more than a 90 percent eclipse. At any point where the sun is even partially visible, its not safe for the naked eye.In that region, in totality, its safe to look at it without protection. You can briefly take (viewing glasses) off and look before you put them back on.

Is there any way, besides getting safety glasses, to prepare for the eclipse?

Leonardi:Even animals, youll start to hear nighttime animal sounds because they get fooled, too. Its so outside normal experience that you cant honestly prepare for it. Its not like when daytime turns to night, its much different than that.

What’s the best way to enjoy the eclipse itself?

Leonardi: You definitely want to give yourself time before the eclipse to see the approach. The eclipse itself lasts for a couple of minutes, but you want to see all the subtle changes first. If they can tear their eyes away for those two minutes, take a little time to glance at the horizon because youll see some weird, unique effects. Youll see sort of sunset effects all across the horizon. … I would just urge people to do it safely.

Yarborough: Probably the most important thing everyone knows is they need to protect their eyes. Looking up at the sun, even briefly, can do real damage to your eyes. Ordinary sunglasses simply will not protect their eyes from looking up at an eclipse.Its an exciting event, one everyone ought to see. For anybody whos interested, it (traveling to the area of totality) would be worth it. Once you get 10 miles or so south or southwest of Spartanburg, youll be in the edge of the total region. The difference will be noticeable. Anywhere in South Carolina will experience a partial eclipse, however, which is still a sight to see. It wont be something to forget.

Everyone will be looking up on Monday, August 21, when whats being called the Great American Eclipse sweeps across the U.S.

I really encourage you to be in a place where you can see the total solar eclipse, says Bill Nye, known as the Science Guy from his popular 1990s-era PBS kids show. This one moment where the Earth, moon and sun are in a lineit really is spectacular, says Nye, 61, who serves as the CEO of the Planetary Society in Pasadena, California, and is star of Bill Nye Saves the World on Netflix.

Check out these eclipse must-knows from Nye and astronomy whiz kids Cannan and Carson Huey-You.

The sunlight filtering around the advancing moon creates alternating bands of light and dark on the ground racing across the land. Its crazy; theyre several football fields wide, and they move over you. Its otherworldly and spooky, Nye says.

This aura of gasses that surrounds the sun and shoots out into space for millions of miles is spectacularly visible to the unaided eye as a brilliant, glowing halo during the total eclipse.

The amount of time it will take for the eclipse to zoom across the entire continent.

The longest anyone, anywhere will be able to witness its totalitythats in Hopkinsville, Kentucky.

Unlike most other total eclipses, the 2017 eclipse will cross directly overheador nearbymany major population areas. Its going right across the United States, Nye says. Take a felt-tip marker and draw from Oregon to Georgia, and there it is.

Thats how long ago the previous coast-to-coast solar eclipse was last seen in the U.S. There will be another total solar eclipse in July 2019, but it will be visible only in parts of Argentina and Chile. The truth is, eclipses arent all that rare. Total solar eclipses occur every two years, says Nye, author of the just-released Everything All at Once. They come in pairs. Theyre more frequent than presidential elections! Most are visible only to relatively few people or from places where many people cant easily goremote mountaintops, the middle of an ocean, unpopulated areas hundreds or thousands of miles away from anything else. That makes the 2017 eclipse extra special.

During the total eclipse, as the light from the sun is blocked, these points of light begin to appear as sunlight streams through the valleys of the moons horizon.

In a total eclipse, the moons shadow flies across the face of the planet at supersonic speed. Thats fastalmost as fast as it took Carson Huey-You and his younger brother, Cannan, science-minded kid geniuses in the Dallas area, to zip far ahead academically of most kids their age.

Carson, 15, enrolled in Texas Christian University when he was 11 and graduated in May with a degree in physics and minors in math and Chinese. He plans to continue with graduate studies in physics toward a masters degree and ultimately a doctorate. Cannan, 11, will enter TCU this fall to study engineering and astrophysics.

Here are 10 things Carson and Cannan want you to know about the upcoming eclipse.

NASA has selected nine proposals in its Explorers Program to study the Sun and general space environment. There are five Heliophysics Small Explorer mission proposals, two Explorer Missions of Opportunity Small Complete Mission (SCM) proposals, and one Partner Mission of Opportunity (PMO).

According to the press release, the Heliophysics Small Explorer missions and Explorer Missions of Opportunity SCM missions will be have specific explorations, including weather in the near-Earth environment, magnetic energy, solar wind, and heating and energy released in the atmosphere. The mission in the PMO category will be more focused on creating space instruments.

Ultimately, these missions will all help scientists better understand the influence of the Sun on our solar system, including the planets and the space between them.

The Heliophysics Small explorer proposals will be given $1.25 million for an 11-month mission concept study. Those missions are: Mechanisms of Energetic Mass Ejection eXplorer (MEME-X), Focusing Optics X-ray Solar Image (FOXSI), Multi-Slit Solar Explorer (MUSE), The Tandem Reconnection and Cusp Electrodynamics Reconnaissance Satellites (TRACERS), and the Polarimeter to Unify the Corona and Heliosphere (PUNCH) mission.

MEME-X will study how charged particles leave Earths atmosphere, while TRACERS will study Earths magnetopause, which is the boundary between our planets magnetosphere and the incoming charged particles of the solar wind. FOXSI and MUSE will focus on the Suns atmosphere and the mysterious solar corona, which is only visible from Earth during a total solar eclipse. PUNCH will take a closer look at the solar wind.

The two Each Mission of Opportunity SCM proposals will be given $400,000 for an 11-month concept study. Those proposals are: the Sun Radio Interferometer Space Experiment (SunRISE) and the Atmospheric Waves Experiment (AWE) mission.

SunRISE will create a radio telescope array from miniature satellites to study how the Sun releases particles into space. AWE will look back at Earth to study a phenomenon known as gravity waves, which transport energy throughout a planets atmosphere.

The final proposal is in the Partner Mission of Opportunity category and will study three instruments on the Turbulence Heating ObserveR (THOR) mission, a mission that the European Space Agency is considering. THOR looks at how particles in space gain and lose energy.

This artists impression of SN 2017egm shows the power source for this extraordinarily bright supernova. The explosion was triggered by a massive star that collapsed to form a neutron star with an extremely strong magnetic field and rapid spin, called a magnetar. Debris from the supernova explosion is shown in blue and the magnetar is shown in red. Credit: M. Weiss/CfA

Many rock stars dont like to play by the rules, and a cosmic one is no exception. A team of astronomers has discovered that an extraordinarily bright supernova occurred in a surprising location. This heavy metal supernova discovery challenges current ideas of how and where such super-charged supernovas occur.

Supernovas are some of the most energetic events in the Universe. When a massive star runs out of fuel, it can collapse onto itself and create a spectacular explosion that briefly outshines an entire galaxy, dispersing vital elements into space.

In the past decade, astronomers have discovered about fifty supernovas, out of the thousands known, that are particularly powerful. These explosions are up to 100 times brighter than other supernovas caused by the collapse of a massive star.

Following the recent discovery of one of these superluminous supernovas, a team of astronomers led by Matt Nicholl from the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass., has uncovered vital clues about where some of these extraordinary objects come from.

Cambridge Universitys Gaia Science Alerts team discovered this supernova, dubbed SN 2017egm, on May 23, 2017 with the European Space Agencys Gaia satellite. A team led by Subo Dong of the Kavli Institute for Astronomy and Astrophysics at Peking University used the Nordic Optical Telescope to identify it as a superluminous supernova.

SN 2017egm is located in a spiral galaxy about 420 million light years from Earth, making it about three times closer than any other superluminous supernova previously seen. Dong realized that the galaxy was very surprising, as virtually all known superluminous supernovas have been found in dwarf galaxies that are much smaller than spiral galaxies like the Milky Way.

Building on this discovery, the CfA team found that SN 2017egms host galaxy has a high concentration of elements heavier than hydrogen and helium, which astronomers call metals. This is the first clear evidence for a metal-rich birthplace for a superluminous supernova. The dwarf galaxies that usually host superluminous supernovas are known to have a low metal content, which was thought to be an essential ingredient for making these explosions.

Superluminous supernovas were already the rock stars of the supernova world, said Nicholl. We now know that some of them like heavy metal, so to speak, and explode in galaxies like our own Milky Way.

If one of these went off in our own Galaxy, it would be much brighter than any supernova in recorded human history and would be as bright as the full Moon, said co-author Edo Berger, also of the CfA. However, theyre so rare that we probably have to wait several million years to see one.

The CfA researchers also found more clues about the nature of SN 2017egm. In particular, their new study supports the idea that a rapidly spinning, highly magnetized neutron star, called a magnetar, is likely the engine that drives the incredible amount of light generated by these supernovas.

While the brightness of SN 2017egm and the properties of the magnetar that powers it overlap with those of other superluminous supernovas, the amount of mass ejected by SN 2017egm may be lower than the average event. This difference may indicate that the massive star that led to SN 2017egm lost more mass than most superluminous supernova progenitors before exploding. The spin rate of the magnetar may also be slower than average.

These results show that the amount of metals has at most only a small effect on the properties of a superluminous supernova and the engine driving it. However, the metal-rich variety occurs at only about 10% of the rate of the metal-poor ones. Similar results have been found for bursts of gamma rays associated with the explosion of massive stars. This suggests a close association between these two types of objects.

From July 4th, 2017 until September 16th, 2017 the supernova is not observable because it is too close to the Sun. After that, detailed studies should be possible for at least a few more years.

This should break all records for how long a superluminous supernova can be followed, said co-author Raffaella Margutti of Northwestern University in Evanston, Illinois. Im excited to see what other surprises this object has in store for us.

The CfA team observed SN 2017egm on June 18th with the 60-inch telescope at the Smithsonian Astrophysical Observatorys Fred Lawrence Whipple Observatory in Arizona.

A paper by Matt Nicholl describing these results was recently accepted for publication in The Astrophysical Journal Letters, and is available online. In addition to Berger and Margutti, the co-authors of the paper are Peter Blanchard, James Guillochon, and Joel Leja, all of the CfA, and Ryan Chornock of Ohio University in Athens, Ohio.

A copy of the paper isavailable online.

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.

Jupiters Great Red Spot is a hurricane-like storm about 10,200 miles (16,500km) wide and at least 150 years old. On July 10, the Juno spacecraft will complete the first ever up-close study of this storm, flying 5,600 miles (9,000km) above the Great Red Spot. In preparation for this landmark opportunity to observe some of our solar systems most extreme weather, the Gemini and Subaru Telescopes on Mauna Kea have taken some stunning images of Jupiter to supplement the data Juno is expected to obtain.

Why are Earth-based observations so important, when Juno is sitting in orbit around the giant planet? Observations with Earth’s most powerful telescopes enhance the spacecraft’s planned observations by providing three types of additional context, Juno science team member Glenn Orton of NASA’s Jet Propulsion Laboratory explained in a press release. We get spatial context from seeing the whole planet. We extend and fill in our temporal context from seeing features over a span of time. And we supplement with wavelengths not available from Juno. The combination of Earth-based and spacecraft observations is a powerful one-two punch in exploring Jupiter.

The infrared image obtained with the Gemini North Telescopes Near-InfraRed Imager (NIRI) on May 18 allowed astronomers to probe the uppermost regions of Jupiters atmosphere. As one of the highest-altitude features on the planet, the Great Red Spot appears as a bright white oval with narrow streaks on either side. These streaks are thought to be atmospheric features undergoing stretching by the storms high winds.

On the same night, the Subaru Telescope imaged Jupiter using its Cooled Mid-Infrared Camera and Spectrometer (COMICS). This data revealed structures further down inside the storm, such as its cold and cloudy interior increasing toward its center, with a periphery that was warmer and clearer, said Orton.

July 4, 2017 by Tim Stephens A false color image shows the spiral galaxy NGC 3359, which is about 50 million light years from us. NGC 3359 appears to be devouring a much smaller gas-rich dwarf galaxy, nicknamed the Little Cub, which contains 10,000 times fewer stars than its larger companion. The contour lines show where the gas is being stripped from the Little Cub, whose stars are located in the central blue circle. Credit: SDSS Collaboration

A primitive galaxy that could provide clues about the early universe has been spotted by astronomers as it begins to be consumed by a gigantic neighboring galaxy.

The Little Cub galaxyso called because it sits in the Ursa Major or Great Bear constellationis being stripped of the gas needed to continue forming stars by its larger companion. The find means scientists now have a rare opportunity to observe a dwarf galaxy as its gas is removed by the effects of a nearby giant galaxy to learn more about how this process happens.

As the Little Cub has remained almost pristine since its formation, scientists also hope its elements will reveal more about the chemical signature of the universe just minutes after the Big Bang.

The research, carried out by UC Santa Cruz and Durham University, UK, is being presented on Tuesday, July 4, at the Royal Astronomical Society’s National Astronomy Meeting.

The Little Cub and its larger neighbor, a spiral galaxy called NGC 3359, are about 200 to 300 thousand light years apart, and approximately 50 million light years from Earth. Gas from the Little Cub is being stripped away by its interaction with NGC 3359, which has up to 10,000 times as many stars as the Little Cub and is similar to our Milky Way. By observing this cosmic feast, scientists hope to understand more about how and when gas is lost from smaller galaxies.

“We may be witnessing the quenching of a near-pristine galaxy as it makes its first passage about a Milky Way-like galaxy,” said lead author Tiffany Hsyu, a graduate student in the Department of Astronomy and Astrophysics at UC Santa Cruz. “It is rare for such a tiny galaxy to still contain gas and be forming stars when it is in close proximity to a much larger galaxy so this is a great opportunity to see just how this process works. Essentially the larger galaxy is removing the fuel that the Little Cub needs to form stars, which will eventually shut down star formation and lead to the smaller galaxy’s demise.”

The researchers also hope to gain an insight into the make-up of the very early universe by studying the hydrogen and helium atoms that are being illuminated by the small number of very bright stars within the Little Cub (which also has the less romantic name SDSS J1044+6306). Since this galaxy is so primitive, it may still preserve the hydrogen and helium atoms that were created minutes after the Big Bang.

Research coauthor Ryan Cooke, Royal Society University Research Fellow in Durham University’s Centre for Extragalactic Astronomy, said, “We know by studying the chemistry of the Little Cub that it is one of the most primitive objects currently known in our cosmic neighborhood. Such galaxies, which have remained dormant for most of their lives, are believed to contain the chemical elements forged a few minutes after the Big Bang. By measuring the relative number of hydrogen and helium atoms in the Little Cub we might be able to learn more about what made up the Universe in the moments after it began 13.7 billion years ago.”

The researchers hope further observations will find more pristine galaxies where the chemical signature of the early universe might be found.

The Little Cub was initially identified as a potentially pristine dwarf galaxy in data from the Sloan Digital Sky Survey (SDSS). Follow-up observations were conducted using the 3-meter Shane Telescope at Lick Observatory and the 10-meter Keck II telescope at the W.M. Keck Observatory.

“The Little Cub’s discovery is a terrific example of using the smaller 3-meter-class Lick Observatory to scan through hundreds of candidates before focusing on the best sources with UC’s 10-meter Keck telescope,” said coauthor J. Xavier Prochaska, professor of astronomy and astrophysics at UC Santa Cruz.

A paper describing the discovery of Little Cub has been submitted for publication in the Astrophysical Journal Letters.

Explore further: Hubble scopes out a galaxy of stellar birth

This image displays a galaxy known as ESO 486-21 (with several other background galaxies and foreground stars visible in the field as well). ESO 486-21 is a spiral galaxyalbeit with a somewhat irregular and ill-defined …

This dramatic image shows the NASA/ESA Hubble Space Telescope’s view of dwarf galaxy known asNGC 1140, which lies 60 million light-years away in the constellation of Eridanus. As can be seen in this image NGC 1140 has an …

Galaxies today fall roughly into two categories: elliptically-shaped collections of reddish, old stars that formed predominantly during a period early in the history of the universe, and spiral shaped objects dominated by …

The Sculptor Dwarf Galaxy, pictured in this new image from the Wide Field Imager camera, installed on the 2.2-metre MPG/ESO telescope at ESO’s La Silla Observatory, is a close neighbour of our galaxy, the Milky Way. Despite …

Despite being less famous than their elliptical and spiral galactic cousins, irregular dwarf galaxies, such as the one captured in this NASA/ESA Hubble Space Telescope image, are actually one of the most common types of galaxy …

The drizzle of stars scattered across this image forms a galaxy known as UGC 4879. UGC 4879 is an irregular dwarf galaxyas the name suggests, galaxies of this type are a little smaller and messier than their cosmic cousins, …

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She and Travis shared the experience with some of the hospitality workers at the popular tourist spot, taking turns to look throughspecial eclipse glasses that make it safe to watch.

“The sun was setting over the mountains and it was a partial eclipse, so it looked like the cookie monster had taken a bite out of the sun,” said Templeman.

Although it was fascinating to watch through the safety of the glasses, there was no noticeable difference in the daylight.

Templeman said she and Travis knew about this year’s total solar eclipse at the time, and immediately decided to make sure they were were in the U.S. to see it.

The path of “totality,” where the moon will completely obscure the sunlight, stretches from Oregon to South Carolina. In those states, millions of people will experience approximately 2 minutes of darkness in the middle of the day.

Templeman said her family chose the city of Columbia, Missouri because they have friends there.

However, it is also one of the places where the darkness is expected to last the longest. The feeling of night during the day is expected to be so convincing that birds and other animals will begin their evening routines.

A map of the the path of the August 21, 2017 total solar eclipse. (CBC News)

Templeman said it was lucky she had booked accommodation early because she had heard many local hotels around Columbia had no vacancies, with numerous parties and events planned in the city that day.

Templeman is one of many Canadians travelling south for the event.

“It will be really interesting to see a bunch of like-minded people congregate,” she said.

“It’s a really small band across the U.S. that you’ll be able to see, or not see, the sun.”

Although the path of totality is entirely in the U.S., NASA predictions indicate that a partial eclipse will still be visible in parts of Canada. About 80 per cent of the sun is expected to be covered by the moon for those watching from Regina.

Looking at the eclipse can seriously damage a person’s eyes. Anyone planning to watch needs special eclipse glasses, which can be found online or at some science stores or science centres. Do not look at the sun, even if a sliver of it is visible.

Templeman is not sure how she will feel when darkness falls over the crowd.

Astronomy is a natural science. It is the study of everything outside the atmosphere of Earth.

It studies celestial objects (such as stars, galaxies, planets, moons, asteroids, comets and nebulae) and processes (such as supernovae explosions, gamma ray bursts, and cosmic microwave background radiation). This includes the physics, chemistry of those objects and processes.

A related subject, physical cosmology, is concerned with studying the Universe as a whole,[1] and the way the universe changed over time.

The word astronomy comes from the Greek words astron which means star and nomos which means law.[2] A person who studies astronomy is called an astronomer.

Astronomy is one of the oldest sciences. Ancient people used the positions of the stars to navigate, and to find when was the best time to plant crops. Astronomy is very similar to astrophysics. Since the 20th century there have been two main types of astronomy, observational and theoretical astronomy. Observational astronomy uses telescopes and cameras to observe or look at stars, galaxies and other astronomical objects. Theoretical astronomy uses maths and computer models to predict what should happen. The two often work together, the theoretical predicts what should happen and the observational shows whether the prediction works.

Astronomy is not the same as astrology, the belief that the patterns the stars and the planets may affect human lives.

Early astronomers used only their eyes to look at the stars. They used maps of the constellations and stars for religious reasons and also to work out the time of year.[3] Early civilisations such as the Maya people and the Ancient Egyptians built simple observatories and drew maps of the stars positions. They also began to think about the place of Earth in the universe. For a long time people thought Earth was the center of the universe, and that the planets, the stars and the sun went around it. This is known as the geocentric model of the Universe.

Ancient Greeks tried to explain the motions of the sun and stars by taking measurements.[4] A mathematician named Eratosthenes was the first who measured the size of the Earth and proved that the Earth is a sphere. A theory by another mathematician named Aristarchus was, that the sun is in the center and the Earth is moving around it. This is known as the Heliocentric model. Only a small group of people thought it was right. The rest continued to believe in the geocentric model. Most of the names of constellations and stars come from Greeks of that time.[5]

Arabic astronomers made many advancements during the Middle Ages including improved star maps and ways to estimate the size of the Earth.[6]

During the renaissance a priest named Nicolaus Copernicus thought, from looking at the way the planets moved, that the Earth was not the center of everything. Based on previous works, he said that the Earth was a planet and all the planets moved around the sun. This heliocentrism was an old idea. A physicist called Galileo Galilei built his own telescopes, and used them to look more closely at the stars and planets for the first time. He agreed with Copernicus. Their ideas were also improved by Johannes Kepler and Isaac Newton who invented the theory of gravity. At this time the Catholic Church decided that Galileo was wrong. He had to spend the rest of his life under house arrest.[7]

After Galileo, people made better telescopes and used them to see farther objects such as the planets Uranus and Neptune. They also saw how stars were similar to our Sun, but in a range of colours and sizes. They also saw thousands of other faraway objects such as galaxies and nebulae.

The 20th century saw important changes in astronomy.

In 1931, Karl Jansky discovered radio emission from outside the Earth when trying to isolate a source of noise in radio communications, marking the birth of radio astronomy and the first attempts at using another part of the electromagnetic spectrum to observe the sky. Those parts of the electromagnetic spectrum that the atmosphere did not block were now opened up to astronomy, allowing more discoveries to be made.

The opening of this new window on the Universe saw the discovery of entirely new things, for example pulsars, which sent regular pulses of radio waves out into space. The waves were first thought to be alien in origin because the pulses were so regular that it implied an artificial source.

The period after World War 2 saw more observatories where large and accurate telescopes are built and operated at good observing sites, normally by governments. For example, Bernard Lovell began radio astronomy at Jodrell Bank using leftover military radar equipment. By 1957, the site had the largest steerable radio telescope in the world. Similarly, the end of the 1960s saw the start of the building of dedicated observatories at Mauna Kea in Hawaii, a good site for visible and infra-red telescopes thanks to its high altitude and clear skies.

The next great revolution in astronomy was thanks to the birth of rocketry. This allowed telescopes to be placed in space on satellites.

Satellite-based telescopes opened up the Universe to human eyes. Turbulence in the Earth’s atmosphere blurs images taken by ground-based telescopes, an effect known as seeing. It is this effect that makes stars “twinkle” in the sky. As a result, the pictures taken by satellite telescopes in visible light (for example, by the Hubble Space Telescope) are much clearer than Earth-based telescopes, even though Earth-based telescopes are very large.

Space telescopes gave access, for the first time in history, to the entire electromagnetic spectrum including rays that had been blocked by the atmosphere. The X-rays, gamma rays, ultraviolet light and parts of the infra-red spectrum were all opened to astronomy as observing telescopes were launched. As with other parts of the spectrum, new discoveries were made.

From 1970s satellites were launched to be replaced with more accurate and better satellites, causing the sky to be mapped in nearly all parts of the electromagnetic spectrum.

Discoveries broadly come in two types: bodies and phenomena. Bodies are things in the Universe, whether it is a planet like our Earth or a galaxy like our Milky Way. Phenomena are events and happenings in the Universe.

For convenience, this section has been divided by where these astronomical bodies may be found: those found around stars are solar bodies, those inside galaxies are galactic bodies and everything else larger are cosmic bodies.

Diffuse Objects:

Compact Stars:

Burst events are those where there is a sudden change in the heavens that disappears quickly. These are called bursts because they are normally associated with large explosions producing a “burst” of energy. They include:

Periodic events are those that happen regularly in a repetitive way. The name periodic comes from period, which is the length of time required for a wave to complete one cycle. Periodic phenomena include:

Noise phenomena tend to relate to things that happened a long time ago. The signal from these events bounce around the Universe until it seems to come from everywhere and varies little in intensity. In this way, it resembles “noise”, the background signal that pervades every instrument used for astronomy. The most common example of noise is static seen on analogue televisions. The principal astronomical example is: Cosmic background radiation.

There are way astronomers can get better pictures of the heavens. Light from a distant source reaches a sensor and gets measured, normally by a human eye or a camera. For very dim sources, there may not be enough light particles coming from the source for it to be seen. One technique that astronomers have for making it visible is using integration, (which is like longer exposures in photography).

Astronomical sources do not move much: only the rotation and movement of the Earth causes them to move across the heavens. As light particles reach the camera over time, they hit the same place making it brighter and more visible than the background, until it can be seen.

Telescopes at most observatories (and satellite instruments) can normally track a source as it moves across the heavens, making the star appear still to the telescope and allowing longer exposures. Also, images can be taken on different nights so exposures span hours, days or even months. In the digital era, digitised pictures of the sky can be added together by computer, which overlays the images after correcting for movement.

With radio telescopes smaller telescopes can be combined together to create a big one, which works like one as big as the distance between the two smaller telescopes.

Adaptive optics means changing the shape of the mirror or lens while looking at something, to see it better.

Data analysis is the process of getting more information out of an astronomical observation than by simply looking at it. The observation is first stored as data. This data will then have various techniques used to analyse it.

Fourier analysis in mathematics can show if an observation (over a length of time) is changing periodically (changes like a wave). If so, it can extract the frequencies and the type of wave pattern, and find many things including new planets.

A good example of a fields comes from pulsars which pulse regularly in radio waves. These turned out to be similar to some (but not all) of a type of bright source in X-rays called a Low-mass X-ray binary. It turned out that all pulsars and some LMXBs are neutron stars and that the differences were due to the environment in which the neutron star was found. Those LMXBs that were not neutron stars turned out to be black holes.

This section attempts to provide an overview of the important fields of astronomy, their period of importance and the terms used to describe them. It should be noted that astronomy in the Modern Era has been divided mainly by electromagnetic spectrum, although there is some evidence this is changing.

Solar astronomy is the study of the Sun. The Sun is the closest star to Earth at around 92 million (92,000,000) miles away.[8] It is the easiest to observe in detail. Observing the Sun can help us understand how other stars work and are formed. Changes in the Sun can affect the weather and climate on Earth. A stream of charged particles called the Solar wind is constantly sent off from the Sun. The Solar Wind hitting the Earth’s magnetic field causes the northern lights.[9] Studying the Sun helped people understand how nuclear fusion works.

Planetary Astronomy is the study of planets, moons, dwarf planets, comets and asteroids as well as other small objects that orbit stars. The planets of our own Solar System have been studied in depth by many visiting spacecraft such as Cassini-Huygens (Saturn) and the Voyager 1 and 2.

Galactic Astronomy is the study of distant galaxies. Studying distant galaxies is the best way of learning about our own galaxy, as the gases and stars in our own galaxy make it difficult to observe. Galactic Astronomers attempt to understand the structure of galaxies and how they are formed through the use of different types of telescopes and computer simulations.

Hydrodynamics is used in astronomy for mathematically modelling how gases behave. Strong magnetic fields found around many bodies can drastically change how these gases behave, affecting things from star formation to the flows of gases around compact stars. This makes MHD an important and useful tool in astronomy.

Gravitational wave astronomy is the study of the Universe in the gravitational wave spectrum. So far, all astronomy that has been done has used the electromagnetic spectrum. Gravitational Waves are ripples in spacetime emitted by very dense objects changing shape, which include white dwarves, neutron stars and black holes. Because no one has been able to detect gravitational waves directly, the impact of Gravitational Wave Astronomy has been very limited.